Having a deck associated with a residence or a commercial building, such as a bar or restaurant is highly desirable since it provides a place for outdoor gatherings. The presence of a deck enhances the value of the real estate of the residence or building. People have a natural preference for the outdoors when the weather is nice, whether one is having a backyard barbeque or relaxing with friends and neighbors. Restaurant patrons typically request outdoor seating on nice days and evenings, and often will wait for a table to become available, even though they could be seated indoors immediately.
Typically, the structural members of a deck are made from pressure-treated yellow pine. Pressure-treated wood is preferred for the structure of a deck because of its reasonable cost and high resistance to insect and moisture damage. However, deck surfaces made of pressure treated yellow pine tend to check, split, cup, twist and splinter after prolonged exposure to the elements. In addition, yellow pine is a relatively soft wood and is subject to wear, particularly in high-traffic areas of a deck. Thus, every few years the property owner is confronted with the considerable expense of both money and labor in having to replace deck boards.
In response to the deficiencies of pressure treated yellow pine decking, many homeowners and contractors are now specifying alternative materials for decking, such as redwood, cedar, manmade composite materials or tropical hardwoods. Recently, composite lumber has been introduced as a candidate for deck board materials. Composite lumber is an attractive material choice for deck boards because it is substantially rot-free. Composite lumber is constructed of plastic and wood materials, such as blends of scrap and/or scrap materials. The materials used include, but are not limited to: plastic bags, plastic jugs (such as those used for milk and water), plastic scraps, wood materials such as sawdust and ground-up wood scraps. Higher quality composite lumber may be constructed of virgin plastics such as polyethylene, polypropylene, and ground-up wood scraps. Higher quality composites may offer a more genuine wood-like appearance when compared to lesser grades. Composite wood decking products are available from Fiberon Composites of New London N.C., and the Trex Corporation of Winchester VA, to name just two possible vendors.
Composite lumber products are environmentally sound because they may contain a significant amount of recycled plastic. Composite lumber does not split, check or splinter, making a safe splinter free surface for bare feet and children. However, composite lumber is significantly more expensive than standard pressure treated yellow pine decking. A quality installation is essential to preserve the significant investment in material.
Plastic lumber is available in standard lumber dimensions (5/4 and 2×) as well as custom configurations. Plastic lumber can be cut, shaped and installed using standard tools and fasteners. Decking, railings and banisters are popular applications for composite lumber. Joists used to support plastic decking are frequently required to be closer together than the 16 or 24 inches required for 5/4 and 2× wood decking, respectively. More joists make for a more expensive installation having more screws joining the decking to the structure.
The problem with using composite lumber is that conventional deck screws, when drilled into the lumber, create a mound or bump in the vicinity of the screw. Formation of these mounds or bumps is referred to as “volcanoing” or “mushrooming”.
“Volcanoing” is an apt description because the screw sits inside the material that has been raised around the perimeter, and therefore resembles a volcano. It is caused by the action of the screw displacing the composite material as it is driven into the composite material, forcing the material upward. This effect is depicted in FIG. 6, which shows a prior art screw driven into the plastic, and the volcano 51 that surrounds the screw.
To provide the proper finished appearance, the volcano must be hammered or punched back into the board by use of the appropriate tool. While this sometimes is effective, in other instances the appearance of the hammered-down material is not attractive. Also, inadvertently striking the deck surface with a hammer may leave the impression of a hammer head on the deck. Using a punch to do the job eliminates the hammer mark problem, but like using a hammer, it is labor intensive.
Because decks using plastic decking require more floor joists, there are a greater number of screws to install. Even a modest deck requires hundreds of deck screws, making each additional step very expensive in terms of added labor.
Another possible solution to the problem is to pre-drill the screw hole and then insert the screw, but again this is labor intensive and time consuming.